How Should You Design a CCTV System That Actually Works?

CCTV design is the engineering of camera placement, resolution, lighting, network, and storage so recorded video can actually identify people and document events. The engineer models coverage using recognition criteria (pixels per foot at the target distance), then specifies cameras, lenses, mounts, PoE network capacity, video management software, and retention storage to meet it. The mistake I see most is designing from the camera catalog instead of from the threat. A 4K camera with the wrong lens at the wrong height produces worse evidence than a 2MP camera aimed correctly. Coverage first, hardware second — that's the whole discipline in one sentence.

Resolution planning uses DORI criteria — detection, observation, recognition, identification — each requiring more pixels per foot at the target. A parking lot camera that only needs to detect movement is a different design than a lobby camera that must identify a face. I document the required DORI level per camera, because that single decision drives lens selection, camera count, and storage. Lighting is the silent killer of CCTV performance. Cameras need minimum illumination at the target, and backlighting (a bright doorway behind a person) destroys faces. The design coordinates camera positions with the lighting design — and where lighting can't be fixed, I specify wide-dynamic-range cameras or infrared illumination. Network and power engineering follows: PoE budgets per switch, UPS backup for cameras and recorders, and bandwidth calculations so thirty cameras streaming at full resolution don't saturate the building network.

Cameras are the last thing I select, not the first. The design sequence is risk assessment, coverage model, lighting coordination, then hardware. When owners let me run that sequence, the systems hold up in real incidents. Here's the checklist I build into every CCTV design.

• Coverage model per camera: DORI target, distance, and pixels-per-foot documented before any camera is selected
• Lighting coordination: minimum illumination at each target, backlight handled, IR where needed
• Lens and mounting geometry: focal length matched to target distance, heights that see faces not foreheads
• Network and PoE budget: per-switch power and bandwidth calculations, UPS on cameras and recorders
• Retention math: resolution, frame rate, camera count, and retention days sized with real headroom
• Cybersecurity: cameras on a segmented VLAN with hardened credentials, not flat on the corporate network